Table of Contents
International Journal of Evolutionary Biology
Volume 2012, Article ID 897157, 16 pages
Review Article

Divergence in Defence against Herbivores between Males and Females of Dioecious Plant Species

Department of Biology, The University of Winnipeg, Winnipeg, MB, Canada R3B 2G3

Received 29 June 2012; Revised 21 September 2012; Accepted 17 October 2012

Academic Editor: Jeremy L. Marshall

Copyright © 2012 Germán Avila-Sakar and Cora Anne Romanow. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Defensive traits may evolve differently between sexes in dioecious plant species. Our current understanding of this process hinges on a partial view of the evolution of resistance traits that may result in male-biased herbivory in dioecious populations. Here, we present a critical summary of the current state of the knowledge of herbivory in dioecious species and propose alternative evolutionary scenarios that have been neglected. These scenarios consider the potential evolutionary and functional determinants of sexual dimorphism in patterns of resource allocation to reproduction, growth, and defence. We review the evidence upon which two previous reviews of sex-biased herbivory have concluded that male-biased herbivory is a rule for dioecious species, and we caution readers about a series of shortcomings of many of these studies. Lastly, we propose a minimal standard protocol that should be followed in any studies that intend to elucidate the (co)evolution of interactions between dioecious plants and their herbivores.